Hydraulic fracturing increases fluid (e.g., hydrocarbons, and the like) flow from a subterranean zone by creating new fractures and facilitating connectivity of the existing pores and natural channels contained in the subterranean zone. Hydraulic fracturing is a process by which cracks or fractures in the subterranean zone are created by pumping a fracturing fluid at a pressure that exceeds the parting pressure of the rock. The fracturing fluid creates or enlarges fractures in the subterranean zone and a particulate proppant material suspended in the fracturing fluid may be pumped into the created fracture. This process is also known as “frac-packing”. The created fracture continues to grow as more fluid and proppants are introduced into the formation.
The proppants remain in the fractures in the form of a permeable “pack” that serves to hold open or “prop” the fractures open. After placement of the proppant materials, the fracturing fluid may be “broken” and recovered by using a breaker or a delayed breaker system to facilitate a reduction in the viscosity of the fracturing fluid. The reduction in fluid viscosity along with fluid leak-off from the created fracture into permeable areas of the formation allows for the fracture to close on the proppants following the treatment. By maintaining the fracture open, the proppants provide a highly conductive pathway for hydrocarbons and/or other formation fluids to flow into the borehole.
Guar is often used to increase the viscosity of fracturing fluids in order to reduce the amount of wear and/or to facilitate the transport of proppants. As a naturally occurring material, guar is a limited natural resource, the demand for which has increased greatly in recent years. In addition to significant supply limitations, guar-based fracturing fluids are also limited by other significant disadvantages, including but not limited to, the hydration limitations of the guar polymer, formation damage, i.e., undesirable coating of proppant materials and/or formation surfaces with the guar polymer or residue, and instability of the guar polymer at elevated temperatures in certain types of fracturing applications.
It is therefore desirable to provide an alternative to guar-based fracturing fluids, which solves one or more of the above problems associated with these guar-based, fracturing fluids. It is also desirable to provide an alternative to guar-based fracturing fluids whereby the viscosity of the fracturing fluid is controlled.